It is known to provide shaped elongated bodies, especially continuous strands, from thermoplastic synthetic-resin material by plastifying the thermoplastic synthetic resin in a worm-type extrusion press, to force the material through a sieve or like perforated body to degas the material and ensure homogenization thereof, to pass the plastic mass through a die or tool having an aperture of the desired shape, to regulate this profile shape by calibration, tempering and/or cooling or stretching, and to draw the continuous extrusion through a sequence of apparatus units having the aforedescribed function. The term "profiled extrusion" is here used in its most general sense to refer to elongated bodies with angular, prismatic or round cross section and is intended to include tubes or pipe of any cross section. The term is also employed to refer to elongated flat strips, synthetic-resin foils and the like.
In conventional apparatus for this purpose, the worm-rotation speed controller and the extrusion-drawing apparatus are functionally independent from one another at least with respect to the associated control units. The setpoint values of these control systems are, on the one hand, the rate of feed of the synthetic-resin material and, on the other hand, the dimensions of the profiled strand to be produced.
While it can be conceived that the two control units can be functionally related or coupled, the prior art systems have never been able to produce a product of given configuration, dimensions and like parameters in a continuous and reproducible manner within narrow tolerances. The sole purpose of functionally connecting the two control systems in earlier arrangements has been to ensure that the product output per unit time, in terms of the mass of the synthetic resin, remains constant so that the same volume of thermoplastic material passes through all parts of the apparatus per unit time.